Patent Document 1 discloses a hose connection device for tightening a connection portion between a hose and a pipe. The hose connection device disclosed in the document has a hose clamp formed in a ring-like configuration. The hose clamp is formed by bending a strip-like plate spring material into a ring-like shape; at one longitudinal end side thereof there is formed forked a first end portion where an elongated-hole-like through-hole is open. The range of the first end portion including the through-hole is bent in the radial direction to form a first pinching portion. At the other end side of the hose clamp, there is formed a second end portion of a smaller width than the opening width of the through-hole. The second end portion is bent in the radial direction so as to form a second pinching portion opposite the first pinching portion.
The above hose clamp disclosed can maintain the first and second pinching portions brought close to each other in a state in which they are held together by a holder, whereby it is possible to maintain the hose clamp in a state in which its inner diameter is increased. On the other hand, by removing the holder, the hose clamp undergoes transition to a reduced-diameter state due to its own elastic force, making it possible to tighten the connection portion between the hose and the pipe.